Center punch



Jan. 10, 1950 T E, DARNELL 2,494,287

CENTER PUNCH Filed Oct. 23, 1947 mill/)111110K '42' INVENTOR, THU/MJ E @AQ/veu www ATTORNEY Patented Jan. 10, 1950 UNITED STATES PATENT OFFICE 2,494,287 I CENTER PUNCH j Thomas E. Darnell, Detroit, Mich. I i u I Application October 23, 1947, Serial No. 781,589

4 Claims.

My invention relates to a new and useful improvement in a center punch and is intended primarily to provide a device for accurately centering the center punch relatively to the hole in a templet, pattern,` die plate or the like so as to center punch the work-piece accurately relatively to the hole in such pattern or templet,

It is an object of the present invention to provide a center punch so arranged and constructed that it may be readily centered to holes of various sizes.

Another object of the invention is the provision in a center punch of a spring pressed punch so arranged and constructed that it may be released for movement to punching position in response to spring pressure. Another object of the invention is the provision .in a, device of this class of means whereby; the center punch may be moved to position for loading or compressing the spring and retaining the same in such position until released.

Another object of the invention is the provision in a center punch of a housing having a plurality of contact members swingably mounted thereon and swingable outwardly into engagement with '1" a hole in which positioned in order to center the center punch relatively to said hole.

Other objects will appear hereinafter.

It is recognized that various modifications and changes may be made in the detail of structure illustrated without departing from the invention and it is intended that the present disclosure represents one embodimentof the invention.

Forming a part of this specification are drawings in which,

Fig. 1 is a side elevational View of the invention,

Fig. 2 is a central, longitudinal, sectional view of the invention with parts broken away and parts shown in section and other parts shown in side elevation, all slightly enlarged over that shown in Fig. 1.

Fig. 3 is a sectional view taken on line 3 3 of Fig. 2,

Fig. 4 is a sectional view taken on line 4-4 of Fig. 2;

Fig. 5 is a sectional view taken on line 5--5 of Fig. 2,

Fig. 6 is a sectional-view taken on line B-I of Fig. 2,

Fig. 7 is a fragmentary, sectional view taken on line 1-1 of Fig. 2.

In the invention, I provide a housing comprising in part, a barrel II provided with the constricted opening 'I3 formed' therethrough which is internally threaded and which lopens at (me .end

into the recessIZ. Threaded into this'threaded opening `I3 is an externally threaded sleeve"` I4 having a peripheral flange I5 formed in one end thereof. Slidably projected through this sleeve or member I4 is a punch I6 projecting outwardly from which is a pin I1 adapted to engage in .the longitudinal slot I8 formed in the member I4. The chamber I9 of the barrel II terminates in a shoulder 29 on which engages a washer 2l bearing against which is one end of a coil spring 22 which embraces the punch I6. The opposite end of the spring 22 embraces, in snug engagement, the conical portion of a sleeve or tube 23, pro'- jecting upwardly from which, diametrically op:- positely' ofeach other, are the arms 24 and 25, each of which is provided with an engaging prong 2Ii'adapted' to engage behind the head 21 carried on the upper end of the punch-or lrod I6; The lower end of this punch is tapered, as at 14, to provide a center point.

The housing also-comprises an extension tube 29 having a portion 30 reduced in outside diameter and telescoping inwardly of the section II.A The tube 23 projects through the end of this section 29. Formed in the end of the. section 29 -is a peripheral groove'3l in which engages a set screw 32 secured to the section II and projecting at one end into the groove 3| lso that the section -29 is rotatable relatively to the section II while they are in fixed,axialrelation. Also carried bythe lower end of the section 29 is an inwardly pro.- jecting screw 33 which engages in the longitudif nally directed slot 34 formed inthe member 25,'. Slidably engaging in the member., 29 Ais a tube 15 which is slotted intermediate its ends, the slots extending inwardly from one end as ldesignatedby the numerals 35 and 36 so that the end of the tube or member 15 is thus divided into a pairof substantially semi-circular segments in which are formed longitudinally directed slotsA 31 and 38 to provide the oppositely disposed gripping fingers 39 and 40. Projecting inwardly from the end of each of the members 39 and 49 is a grip ping lug 4I adapted to project inwardly beyond the edge of the head 21 so that when the tube 15 is pulled outwardly of the section 29, these members =4I will engage behind the head 21 and move the center punch or rod I6 axially againstl th compression of the spring 5I and the spring '22, the washer 2l moving with the punch or rod AI6'. The members 24 and 25 are' resilient so thatfas the head passes between the projections 26, these members 24 and 25 will spring `outwardly and allow the members 26 to snap inwardly behind the ,head 21 thus holding therod or Acenter punch I6 in its position with the springs I and 22 under compression. Threaded into a threaded bore formed through the member l5 is a screw 42 having a tapered end 44 adapted to engage the inclined faces of the ends of the members 24 and 25. By pressing inwardly of this screw 42, the members 24 and 25 will be swung apart to release the rod or center punch I6 for movement in response to the compression of the springs 5| and 22.

Projecting outwardly from the end of the section Il are knuckles 46 extended through each of which is a pivot pin 41 to pivotally mount the contact leg 4B thereon. As shown in Fig. 3, I prefer to use three of these contact legs, although the number may be increased if desired. Projecting inwardly from adjacent the upper end of each of these legs is a flange or tongue 49 which engages the under surface of a washer 'I6 through which is slidably projected the center punch or rod t6. The nose projects inwardly from the upper end of each of the contact legs and engages the outer face of the ange i5. One end of the spring 5i, which embraces the rod or stem I6,

bears against one face of the washer 16, and the eother end bears against the washer 52 which is secured on the rodi or center punch I6 by means of the pin 53.

The construction is such that when the parts are assembled, as described, the contact legs may he inserted at their ends in an opening 17 formed in the templet, die plate, pattern or the like, indicated by the numeral 'I8 and which is positioned over the work-piece 19 in which it is desired to form a duplicate of the hole 11. The holes 'H formed in the templet or die plate T8 are not all of the same size, but when the legs are inserted into the openings, the section 2S' may be rotated relatively to the section lf and through the engagement of the set screw' 33- andthe slot 34, the tube or sleeve 23 will be rota-ted. As shown in Fig. 5, the rod or punch IB is provided with at faces 28 at that portion which projects through the member 23 which is also provided with hat faces so that the rodor punch I6 is also rotated as the tube 23 rotates, and the member [4- will rotate to move inwardly or outwardly of the section ll because of the engagement of pin Il in slot I8. As it moves inwardly the legs 48 will draw toward each other and as the member i4 moves outwardly, the legs 48 will be pressed outwardly to spread apart. In this manner, the legs may be brought into engagement simultaneously with the inner surface of the opening 11 regardless of the size so long as it is a size within the limits of the mechanism. When this engagement is effected and a tight contact is made with the sidewall of the opening, the center punch I6 will be accurately centered relatively to the opening ll.` Thereupon, upon pressing down on the screw 42, the members 24 and 25 may be sprung apart permitting the center punch I6 to move downwardly in response to compression of the springs 22 and 5| to engage the work-piece 'I9 and center mark the same. The projection of the center punch i6 beyond the end of the housing is such as to extendy slightly beyond the ends of the contact legs 48 when they are in their most contracted position, After the center marking has been eieeted, it is but necessary to again pull` the center punch IB upwardly toA cause the members 28 to engage beneath the head 2l and the device isi again ready for operation. Should it be desired to center punch round stock, the `periphery of 4 such stock may be engaged in the cut-away portions 55 of the ends of the legs.

In this way, I provided a simple and effective device whereby the center punching may be accurately accomplished and the operation easily and quickly performed where it is desired to center punch for a plurality of openings of various sizes. In this way, the use of several tools of diiferent sizes is eliminated and a considerable saving in labor is accomplished, as well as a more accurate and eicient center punching performed.

What I claim as new is:

l. In a center punch of the class described, a housing comprising an upper and a lower tubular section, the upper section telescoping at its lower end with the upper end of said lower section, said sections being relatively rotatable and fixed axially; a center punch slidably projecting at one end into said housing and at its opposite end outwardly beyond the lower end of said lower section, the inner end of said punch being located in said upper section; a sleeve projecting through the lower end of said upper section and extending into said lower section, said sleeve being nonrotatable relatively to said upper section and embracing the inner end of said punch, said punch slidably projecting therethrough and being non-rotatable relatively thereto; a headv on the inner end of said punch; a pair of diametrically opposite spring arms projecting from the upper end of said sleeve and extending toward the upper end of said upper section; and an engaging prong on each of said arms projecting inwardly therefrom adjacent the free end thereof for engaging behind said head and securing Said punch against axial movement.

2. In a center punch of the class described, a housing comprising an upper and a lower tubular section, the upper section telescoping at its lower end with the upper end of said lower section, said sections being relatively rotatable and fixed axially; a center punch slidably projecting at one end into said housing and at its opposite end outwardly beyond the lower end of said lower section, the inner end of said punch being located in said upper section; a sleeve projecting through the lower end of said upper section and extending into said lower section, said sleeve being non-rotatable relatively to said upper section and embracing the inner end of said punch, said punch slidably projecting therethrough and being non-rotatable relatively thereto; a head on the inner end of said punch; apair of diametrically opposite spring arms projecting from the upper end of said sleeve and extending toward the upper end of said upper section; and an engaging prong on each of said arms projecting inwardly therefrom adjacent the free end thereof for engaging behind said head and securing said punch against axial movement; and a threaded member carried by the upper end of said upper section and threadabl'e inwardly and outwardly thereof and adapted upon inward threading for engaging the ends of said arms and springing the same apart for disengaging said prongs from said head.

3. In a center punch of the class described, a housing comprising an upper and a lower tubular section, the upper section telescoping at its lower end with the upper end of said lower section, said sections being relatively rotatable and iixed axially; a center punch slidably projecting at one end into said housing and at its opposite end outwardly beyond the lower end of said lower section, the inner end of said punch being located in Said upper section; a sleeve projecting: through the lower end of said upper section and extending into said lower section, said sleeve being nonrotatable relatively to said upper section and embracing the inner end of said punch, said punch slidably projecting therethrough and being nonrotatable relatively thereto; a head on the inner end of said punch; a pair of diametrically opposite spring arms projecting from the upper end of said sleeve and extending toward the upper end of said upper section; and an engaging prong on each of said arms projecting inwardly therefrom adjacent the free end thereof for engaging behind said head and securing said punch against axial movement; and a threaded member carried by the upper end of said upper section and threadable inwardly and outwardly thereof and adapted 'upon inward threading for engaging the ends of said arms and springing the same apart for disengaging said prongs from said head; and a spring member cooperating with said punch for forcing said punch outwardly of said housing at the lower end thereof upon disengagement of said prongs with said head.

4. In a center punch of the class described, a housing comprising an upper section and a lower section, said sections being axially xed and relatively rotatable; a sleeve mounted in said housing and rotatable in unison with said upper section; a punch slidably projected at one end into said housing and projecting through said sleeve and being axially moveable relatively to said sleeve and non-rotatable relatively thereto; an externally threaded sleeve threaded into the lower end of said lower section, said punch slidably projecting through said sleeve and rotatable in unison with said externally threaded sleeve for transmitting rotative movement to said externally threaded sleeve upon relative rotation of said housing sections; a plurality of legs swingably mounted at one of their ends on the lower end of said lower` section and engageable at their free ends in an opening in a work piece for engaging the sides thereof and centering the punch relatively to said opening; a nose on each of said legs at the end mounted on said housing eng-ageable with the end of said externally threaded sleeve upon outward threading of the same for spreading said legs apart.

THOMAS E. DARNELL.

REFERENCES CITEDl The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 278,225 Crittenden et al. May 22, 1893 718,427 Clement et al Jan. 13, 1903 742,077 Sovelius Oct. 20, 1903 1,225,191 Throckmorton May 8, 1917l 1,316,045 Knight Sept. 16, 1919 1,856,285 LeFever May 3, 1932 1,928,644 Bunker Oct. 3, 1933 2,118,729 Hogan May 24, 1938 2,195,223 Hogan Mar. 26, 1940 2,302,355 Sumner Nov. 17, 1942 2,396,771 Brinson, Sr Mar. 19, 1946 FOREIGN PATENTS Number Country Date 2,983 Great Britain Feb. 5, 1902 

